Shock absorber



May v15, 1923. 1,454,905

F. E. POIN'DEXTER `HOCK ABSORBER Or i na Filed Feb. 24 1920 a4 .l L l Patented May 1,5, 1923.

FRANKLIN E. vIo'I1\i1 ExtrEn, or lDmrroN, TEXAS, 'ASSIGNoRt BY. MESNE ASSIGNMENTS, 'ro BENJAMIN s. DAVIDSON, oF BENTON, TEXAS.

sirocx Assumere.

Application led February 24, 1920, Serial No. 360,666. Renewed September 25, 1922. Serial No,` 596,540.

To all whom it may concern.' Be it known that FRANKLIN E. PoINDEx- TER, a citizen ofthe United States, residing at Denton, in the county of Denton and State of Texas, has invented certain new and useful Improvements in Shock Absorbers, of which the following is a specification.

In the drawing: The improved fluid pressure device comprisesr al cylindrical casing 1, the upper end of which is-closed by a cap 2, threaded to said cylinder'against gasket 3. The cap is provided with plug 4-, for the-introduction of oil or other liquid and an inwardly opening valve 5 which serves as ay means of in. troducing additional fluid, or the vescape of same under certain conditions as will be explained. Y;

The plunger 6, is attached to cap 2, -by

suitable means as threading into same-and extends into cylinder 7, whichfis attached to and carried by a main piston 8, slidably mounted in casing`1. The said plunger is provided with an upwardly opening valve 9, and a port 10, which permits oil and fluid..

to pass from compartment 11, to compart ment 12. The main piston is provided with a ring shaped diaphragml,'extending from thel, piston wall to cylinder 9, and separating the main piston compartment 14, from compartment 12. The diaphragm is provided with a plug 15, which is provided witha constricted passage, and extends above dia- 4r35 phragm 13. v

Cylinder 7, is provided with a port 1.7, which connects compartments 11` and 14.

against a seat 19, preferably of copper and 40 is secured by means of expansion with a tool which throws the outer edge of seat against its retaining wall. The main piston 8, is provided with a partition 20, having formed integral with itl chamber wall 21, which receives cylinder. 7 ,chamber mall 22,4 and 23, which extends.` to lower part' of compartment 24', ormedV by the main piston wall andthe cup 25, the

' said cu being held in place by a screw or"4 .50 screws- VAspring 34,'of an automobile.

The main piston wall is provided with suitable packing rings 27, and oil scraping ring 28, a dirt scraping ring 29, oil port 30, andv a Ylongiimdinal slot or groove ,31, sol shaped to pass over the end of, screw 32, which limits the downward motionl ofthe main piston 8. f Y

Cup 25,- is provided with a port 3,3, leadf ing Vto groove 31, in conjunction with'which it forms an air inlet to compartment .24, and 69 a means 33, of connecting .the main piston l to one of the vibrating members as` the A means rofconnecting the casing 1, yto the other vibrating member as thelframe of the 65 vehicle is shown at 35.

A means at 36. of connecting a bv lper to extend to a similar deviceon the opposite side'of the vehicle. Y l

Valve 5, is held normally in a closed yposi- 7o tion by spring 37 'Spring 36, is'secured t0 valve '5, and in conjunction with the `flexible connectionj38, which is secured to diaphragm 13, forms a valve vopening means theuse of which will be described. f

The pin 40, limits the movementof ball valve 9. l p The' port 41, serves to control fthe pump.- ing action as will be eXpl'ainedfin/th'e opl"eration ofl the device. A

Spring 42, serves to support` the loadwhen the internal pressure isnotsuiiicient todoso. r.

Cup 25, is provided with a small wick hole 44, by means; ofwhich the shackle bearing that attaches to springof vehicle is f lubricated. l The upwardly opening valve 18, is seated The operation of the device is as follows Suppose that the internal pressure ofthe device is atmospheric and that it is attached to ,the vibrating parts of a vehicle asv shown, the inward thrust of 4the main piston being resisted by the 4compression of spring 42.'

When the vehicle4 is put in motion, the pressure exerted on the ymain piston by -95- fspring 34, of the vehicle 'will `vary from time t'o time and the/piston will -movein land `out of shell Vl, under! the inlluence of spring 42. :This movement-ot` the main piston and '4 cylinder .7, which it carries! brings about 100 changes in the volume of compartment 1.1. The consequent pressure changes in said compartment forces oil and air through valve 9, and ort 10, into the main pressure chamber 12. lVhen the volume of compartment 11 is suddenly increased, the pressure is decreased. Oil is forced into said compartment through the constricted port 17, and air is forced in under atmospheric pres sure through port 33, tube 23, and valve 18. The pressure change for a given volume change in compartment 11, is inversely proportional to the air space above the oil in said compartment. The constricted port 17, insures a supply of oil in compartment 11, as

long as there is any oil in the lower part of the main piston chamber 14, which' serves as an oil reservoir. i l

The compartment 12 constitutes and will be hereinafter referred to as the main pres- Y sure chamber, while the compartment 14 coul" stitutes and will be hereinafter referred to as the oil reservoir. The compartment 11 is in reality a pump chamber, and it is to be particularly noted that the pump chamber 1 and the oil reservoir are in communication thru the restricted opening 17. This opening is important in the operation ofthe device, and to emphasize the, importance ,of this feature it will be assumed that the main piston 8 is for any reason caused to move` downward. This of course removes the cylinder 7 defining the'pump chamber downwardly and increases thev area of such chamn ber below theJ plunger 6. Owing tothe restricted opening; 17 however, oil from the reservoir 14 cannot enter the pump chamber 11 with suliicient rapidity to -fill theadditional space thus provided, which ot course is in the nature of a partial vacuum, and hence such space will be filled with air 'roiii the atmosphere entering,r thru passage ill, port 33 and past valve 19. Thus in what may be termed a separating fmovement of the respective elements 1 and 8 of the shock absorber, a quantity of air from the atmos phcre enters the space beneath the pump plunger 6. In the movement of the members 1 and 8 in the opposite direction, that is, toward each other, the main pressure chamber is reduced in size, materially increasing the pressure in such chamber, and at the same time theJ pump plunger 6 moves into pump chamber a correspondingr distance. As the area of the pump chamber is materially less than thaty of the main pressure chamber, the air trapped in the pump chamber as previously described is increased in pressure proportionally greater than the in.. crease in the main pressure chamber. Hence this air in the pump chamber 11 will be forced by the valve 9 and into lthe main pressure chamber. lere it not for the restricted opening,r 17 and the resultant limited flow of oil from the reservoir to the pump chamber, it is apparent that little or any air from the atmosphere would be permitted to enter The air which vis taken in in this pumping process-increases the internal pressure, the main pistonbeing forced down re1easing the pressure onspring 42. This pumping process will continue until the end of the plunger 6, takes a position above port 41, at which point the intaking oi air from the outside is discontinued the air in compartment 11, being lforced back and forth through said port, there being only-slight pressure changes in vsaid compartment.

Valve 5servestwopurposes.V First, it can be used to introduceairinto'the device and sprin 4:2, could thus begdispensed with, the air cus ion allowing the main piston and shellv 1, to move relative to each other underv the vibratory 'iniiuerrce of the. wehicle. Spring 4t2, could alsobe .placed between the vibratingmembers at some point 'without the shell, as indicated at 43. All that is necess ry for the '-puinping process to'be established is that the main'piston and shell 1, shall 'move relative to each other under the aai influence of the vibrations incident tomotion of the vehicle.

The other function of valve 5., iii-conjunction with the liexible connection `and spring' 36, .is to relieve any excesspressure incident to removing the load on the:vehicleT The volume to whichv the devicey will pump is determined by the position of: portal, and theJ length of plunger 6. ln case the load on the vehicle is removed, the vmain piston l would move down until the internal pressure is decreased a corresponding amount. in' cases where the load change is great, as 1n trucks, the excessive downward movement would be objectionable. The length of the iiexible connection 38, limits this downward movement of the main piston by opening valve 5, against the compression of spring 37. Spring 36, is to prevent the breaking of connection 38.

Thus the volume under all lgad conditions is determined by1 the' position of port 41, the length of plunger 6, and the length of com nection 38.

Port 16, serves as an oil and air passage between compartments 12,. and 14. It is made small so that the gradual equalization of the. pressure between said compartments will slow up motion vof main piston gradually.

' The layer 44, of loose material, as felt, is.

. a pump chamber, a hollow plunger connected to the casing and operating in the. cylinder,

. an air inlet to the pump chamber, and V'a restricted opening 'form/ing. a constant communication between the oil reservoir and pump cylinder under all working conditions, whereby to retard'the fiow ofoil between the reservoirand pump chamber' with 'respect to any pump action.

2. A fluid pressure device comprising two main elements slidabl'y connected and adapted to define va main pressure chamber' between them, one of said elements being formed 'to provide an oil reservoir and a pump chamber in4 communication with the reservoir thru a restricted opening, the other of'said elements having a .plunger operating `in the pump chamber whereby the 'flow of oil. to andr from the pump chamber relative to the reservoir is limited by the restricted opening, the tendency to vacuum formationV by the movement of the plunger 'and the corresponding restricted How of oilbeing compensated for by air admitted from the atmosphere.

3. A fluid pressure device comprisinga casing, a piston operativetherein, and deining a main pressure -chamber therebetween, a pump 4including a pump cylinder connected to one of said elements and a plunger connected to the other of said elements, an air inlet to the pump cylinder-belowthe plunger, and means for permitting l a liquid to flow to and from' a pump cylinder under action of theplu'ngenthe said means'preventing a suicient fiow of liquid to said cylinder in a rapid movement of the plunger to compensate for the plunger movement, whereby air is drawn thru said inlet to compensate for the space not occupied by the oil.

Ll. fluid pressure device comprising a, main pressure chamber, a pump for supplying pressure to said chamber and including a pump cylinder and a plunger operative therein, the pump cylinder having an air inlet, and means wholly independent of the air inletfto admit a liquid to the pump cylinderiinder a suction action of the plunger, said means being so restricted as to prevent a liquid admission to fully compensate for the .plunger movement, whereby air will enter the invention, what the pump cylinder thru the air inlet under the vacuum created by the plunger iiiits movement in excess of the fluid supply.

i 5.' A Huid pressure device comprising slidably cooperative members defining a pres-- sure chamber,'a` pump operated in the movcment of the members for supplying pressure `to said chamber, an oil reservoir having a restricted communication under all workingr conditions with the pump, the suction action of the. pump being partially compensated for by the limited admission'of a liquid to the pump, the pump having an air' inlet to admit air under the suction stroke of. vthe pump' to the extent defined by the suction of the pump in excess of the liquidadmission under 'I such suction.

6. A. fluid pressure device comprising a; casing, a piston movable*thereinland forminga pressure chamber between one end 'thereof and tlniecasing, a pump cylinder arranged within the piston, a vpump plunger connected to'and operated by the casing, an

oil reservoir formed bythe interior of the ypiston and a restricted communication open under all working conditions between lsaid reservoir -and pump cylinder below the plunger, said pump cylinder having an air inlet.

7. A 'iuid pressure device comprising a casing, a piston movable therein and orming a pressure chamber between one end thereof and the casing, a pump cylinder arranged within the piston, a pump plunger connected to and operated oy the casing, an oil reservoir formed by the interior of the piston and a restricted communication be-l .tween said reservoir and pump cylinder below the plunger, said pump cylinder having' an air inlet, and a relier` valvev for the presl sure chamber operated in the relative movement of the piston` A 8. A Huid pressure device.,` comprising a casing, a main piston movable therein formed to provide an oil reservoir to contain a constant supply of oil, a pump operable `in the relative movement of the piston and casing, an air inlet open to the suction action of the pump, and a communication between the-pump and oil reservoir open under all working conditions and so restricted that a pump action can neither draw oil from the reservoir nor force oil to the reservoir in complete correspondence with tbe' pump action.

9. A fluid pressure device, comprising a casing, a main-piston movable in'the casing and formed to provide an oil' reservoir containing a constant supply of oil, a pump .including a pump chamber operated in the relative movement,ofthe casing and piston and drawing. upon said reservoirfin suction4 stroke and forcing material fro the pump chamber to the reservoir in pressure stroke,

dtons of the devise, which connecon is sa fes'rlced as to axd ,the How of 0H. bem'eenl the reservan* ami pumpchamber .ln either direction as compared wlh any pump action,

Wheeby; in u suctifm stroke be .suppy of liquid io the pump chamber is less than'the apaclty of the space provided, and m the .pump clambex' away from said reservoir.

l'n testimony whereof afx my signauru.

FRANKLN t ONDEXTER. 

